Accounting policies must be disclosed and changed only for reasonable cause under the Income Computation and Disclosure Standard. Income Computation and Disclosure Standard I governs selection, change and disclosure of significant accounting policies for computing income under business/profession and other income, subordinate to the Income tax Act. It establishes Going Concern, Consistency and Accrual as fundamental assumptions, requires policies to reflect substance over form, forbids recognition of marked to market or expected losses except as permitted, and mandates disclosure of all significant policies and material changes, with transitional treatment for contracts and transactions from the operative date.